What do you need to know about salvaging old brick?

3-27-2020

Quite often we find specifications or owners requesting that we are to use historic salvaged brick to match the building that needs work. Recently I view a specification for salvaging brick from a 1910 Era building that was 4 wythes (4 bricks) thick and all of the brick were to be salvaged for re-use. They were to be re-used in mostly the outer wall of a building in my Michigan environment. Now that’s a mistake…

Brick manufacture in the early part of the 20th century.

Brick at this time in history was normally a tunnel fired brick that needed to be sorted after their cooling. They were sorted for color which meant that the darker the brick the better the vitrification (harder and denser (less porous). The harder brick at the construction of the building now being removed went to the exterior walls. The lesser vitrified brick would be placed within the interior and center wythes respectively.

Brick Variations

Size. Prior to the ASTM (American Society of Testing Materials) standardization of brick, they came in many different sizes and shapes. Just because its old doesn’t mean it matches every building.
Vitrification. Better known as hardness and porosity. This varies greatly in older brick. The firing process was basically to stack them in a pile and place a fire underneath for 3 days and then let them cool down and sort. The bricks closest to the fire were the most vitrified and the outer bricks were much less. Note the brick in the photograph. You are able to see the shadow of a brick that was shielded from the heat by another brick. The darker section received more heat and possibly some ash that worked as flux to reduce the vitrification temperature.

Mortar removal safety

When removing mortar from the brick the dust will normally contain silica. The resulting silica dust when inhaled is a carcinogen. What OSHA (Occupational Safety and Health Association) requires is engineering controls to reduce or eliminate the silica dust from being inhaled by the person removing the old mortar. These can include wetting down the mortar or utilizing a fan system to blow it away from the operator. This is quite serious. Just putting a respirator is not the answer.

Where To Use

If you look at these older buildings in high moisture or freeze-thaw environment you’ll notice the brick does not enter the ground. They sit on a low porosity stone foundation and may even have an even denser stone separating the foundation from the brick. Just keep the brick away from the high levels of moisture and salts.

Conclusion

When using recycled brick, make sure that you are using the darkest hardest most vitrified brick on the exterior if you are in a freeze-thaw environment.